# US 5,348,310 A · Double spiral-wound gasket assembly with leak detection

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- Number: US 5,348,310 A
- Document ID: US5348310A
- Status: Granted
- Kind: A
- Application number: 07/997,437
- Filed: 1992-12-28
- Granted: 1994-09-20
- Earliest claimed: 1992-12-28
- Assignees: The Dow Chemical Company
- Inventors: Calvin J. Browning; Carl D. Mercer; William S. Milligan
- Web page: https://patentgrep.com/patent/US5348310A

## CPC

- G01M 3/04: by detecting the presence of fluid at the leakage point
- G01M 3/223: {for pipe joints or seals}
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

A gasket assembly with double spiral-wound gaskets and a middle draw-off port for leak detection in service with a process fluid featuring 1) an inner primary seal spiral-wound gasket with a high spring rate to hold the process fluid and pressure, 2) an outer secondary seal spiral-wound gasket with a lower spring rate to hold the process fluid temporarily while a new gasket is being installed, 3) inner and outer compression/gauge rings that allow compression of the spiral-wound gaskets to the proper thickness, and 4) a middle compression ring between the two spiral-wound gaskets that also provides a groove on each side in communication with a draw-off port for monitoring leakage from the inner gasket.

## Claims

### Claim 1

A gasket assembly, comprising from an inner to an outer diameter:
a) an inner compression gauge ring having an inner and outer edge;
b) a first spiral-wound gasket having an inner and an outer winding, said inner winding wrappingly abutting the outer edge of said inner compression gauge ring;
c) a middle compression and gauge ring having an inner and an outer edge, said inner edge abutting the outer winding of said first spiral-wound gasket and having a centrally located groove in both an upper face and a lower face of said middle compression ring for collecting fluid leakage past said first spiral-wound gasket said centrally located grooves having drawoff ports therethrough whereby fluid collected in said grooves can be monitored by a sensing device;
d) a second spiral-wound gasket having an inner and an outer winding, said inner winding wrappingly abutting the outer edge of said middle compression ring; and
e) an outer compression gauge ring having an inner and an outer edge, said inner edge abutting the outer winding of said second spiral-wound gasket.

### Claim 2 (depends on 1)

A gasket assembly as in claim 1 wherein said first and said second spiral-wound gaskets are thicker than said compression gauge rings thereby allowing for compression of said spiral-wound gaskets.

### Claim 3 (depends on 1)

A gasket assembly as in claim 1 wherein said inner compression and gauge ring supports said first spiral-wound gasket and prevents it from unwinding.

### Claim 4

A flange assembly for detecting the leakage of process fluid between the flanges of a process unit connection or pipeline, said flange assembly comprising a gasket assembly comprising from an inner to an outer diameter:
a) an inner compression gauge ring having an inner edge and an outer edge;
b) a first spiral-wound gasket having an inner and an outer winding, said inner winding wrappingly abutting the outer edge of said inner compression gauge ring;
c) a middle compression gauge ring having an inner and an outer edge, said inner edge abutting the outer winding of said first spiral-wound gasket and having a centrally located groove in both an upper face and a lower face of said middle compression ring for collecting fluid leakage past said first spiral-wound gasket said centrally located groove having drawoff ports therethrough, whereby fluid flow past said gasket can be monitored by a sensing device;
d) a second spiral-wound gasket having an inner and an outer winding, said inner wrappingly abutting the outer edge of said second spiral-wound gasket; and
e) an outer compression gauge ring, having an inner and an outer edge, said inner edge abutting the outer winding of said second spiral-wound gasket.

### Claim 5 (depends on 4)

A flange assembly as recited in claim 4 wherein said carrier fluid is a gas which is selected from helium and nitrogen.

### Claim 6

A method fop detecting process fluid leakage between flanges of a process unit or pipeline, comprising the steps of:
a) affixing between a pair of opposing flanges a double spiral-wound gasket assembly comprising from an inner to an outer diameter;
1) an inner compression gauge ring having an inner and an outer edge;
2) a first spiral-wound gasket having an inner and an outer winding, said inner winding wrappingly abutting the outer edge of said inner compression gauge ring;
3) a middle compression gauge ring having an inner and an outer edge, said inner edge abutting the outer winding of said first spiral-wound gasket and having a centrally located groove in both an upper face and a lower face of said middle compression ring for collecting fluid leakage past said first spiral-wound gasket said centrally located grooves having drawoff ports therethrough whereby fluid collected in said grooves can be monitored by a sensing device;
4) a second spiral-wound gasket having an inner and an outer winding, said inner winding wrappingly abutting the outer edge of said middle compression ring; and
5) an outer compression gauge ring, having an inner and an outer edge, said inner edge abutting the outer winding of said second spiral=wound gasket.
b) purging said gasket assembly with a purge carrier fluid; and
c) analyzing said purge carrier fluid.

### Claim 7 (depends on 6)

A method as in claim 6 wherein said carrier fluid is a purge gas which is selected from nitrogen or helium.

### Claim 8 (depends on 7)

A method as in claim 7 further comprising the step of analyzing said process fluid in a mixture of said purge gas and said process fluid.